A gear pump rotor is provided including a combination of an inner rotor and an outer rotor whose numbers of teeth are different by one, and the discharge amount of the pump is increased by an increase of the tooth depth. At least one of an addendum curve and a dedendum curve of an inner rotor is formed by a locus of one point on formation circles that satisfy moving conditions that the formation circles move from moving start points to moving end points while changing the distances from an inner rotor center to the centers of the formation circles. The centers of the formation circles move by a distance in the radial direction of a base circle, and the formation circles rotate by an angle at a constant angular velocity in the same directions of the moving directions of the formation circles.
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1. An internal gear pump rotor that comprises in combination an inner rotor having n-number of teeth and an outer rotor having (n+1)-number of teeth and that sucks and discharges fluid by a change of a capacity of a pump chamber provided between the teeth of the rotors owing to rotations of the rotors,
wherein formation circles move in a manner such as to satisfy the following conditions, and at least one of an addendum curve and a dedendum curve of a tooth profile of the inner rotor is formed by a locus curve drawn, during the movement, by one point that coincides with an addendum bottom or a dedendum top and a reference point on a base circle A concentric with an inner rotor center and that is on the formation circles:
While changing radial distances from the inner rotor center to centers of the formation circles by a distance, the centers of the formation circles move from moving start points where the centers are positioned when the formation circles are arranged so that the point coincides with the reference point on the base circle, to moving end points where the centers are positioned when the formation circles are arranged so that the point is positioned at an addendum top or a dedendum bottom, and the formation circles rotate through an angle of 180° at a constant angular velocity in the same direction as moving directions of the formation circles, wherein a radial distance between the moving start points and the moving end points is the distance,
wherein the centers of the formation circles move from the moving start points to the moving end points while the formation circles reduce diameters thereof, and at least one of the addendum curve and the dedendum curve of the tooth profile of the inner rotor is formed by a locus curve drawn by a point on outer peripheries of the formation circles whose diameters change.
2. The internal gear pump rotor according to
3. The internal gear pump rotor according to
4. The internal gear pump rotor according to
ΔR=R×sin(π/2×m/ST) where ST is the number of steps and m=0→ST.
5. The internal gear pump rotor according to
6. An internal gear pump rotor comprising in combination the inner rotor according to
wherein the center of the inner rotor makes one revolution on a circle centered on a center of the outer rotor and having a diameter (2e+t),
wherein, during this, the inner rotor makes a 1/n rotation,
wherein an envelope of a group of tooth profile curves formed by the revolution and rotation of the inner rotor is drawn,
wherein the outer rotor has the determined envelope as a tooth profile,
and wherein
e: amount of eccentricity between the center of inner rotor and the center of outer rotor
t: tip clearance
n: number of teeth of the inner rotor.
7. An internal gear pump wherein the pump rotor according to
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The present invention relates to an internal gear pump rotor including in combination an inner rotor and an outer rotor whose numbers of teeth are different by one, and to an internal gear pump using the rotor. More specifically, the present invention can increase the theoretical discharge amount of the pump by allowing flexibility in setting the depth and number of teeth.
Internal gear pumps are used, for example, as oil pumps for lubrication of a car engine and for an automatic transmission (AT). In some pump rotors adopted in the internal gear pumps, inner and outer rotors, whose numbers of teeth are different by one, are combined. Further, in some rotors of this type, the tooth profile of the rotor is formed by a trochoidal curve, or the tooth profile of the rotor is formed by a cycloidal curve.
As shown in
As for a tooth profile defined by a cycloidal curve, a tooth profile of an inner rotor is formed by a base circle, a locus of one point on the circumference of an externally rolling circle that does not slip, but rolls on the base circle while being circumscribed about the base circle, and a locus of one point on the circumference of an internally rolling circle that does not slip, but rolls on the base circle while being inscribed in the base circle.
For one tooth profile using a trochoidal curve, one base circle E, one rolling circle F, one locus circle G, and one amount of eccentricity e are set. While it is only necessary to increase the tooth depth in order to increase the discharge amount of a pump having the tooth profile, when the amount of eccentricity e between the inner rotor and an outer rotor is increased to increase the tooth depth, the tooth width becomes too small or it becomes impossible to design the tooth profile. Therefore, the amount of eccentricity e is restricted, and the tooth depth is limited. For this reason, it is difficult to meet the demand to increase the discharge amount.
Further, even when the tooth depth remains the same, the discharge amount can be increased by increasing the number of teeth. However, when the number of teeth increases, the radial dimension of the rotor increases. Thus, it is difficult to meet the demand to increase the discharge amount without changing the outer diameter of the rotor.
This also applies to an internal gear pump that adopts a tooth profile defined using a cycloidal curve. In the pump of this type, the number of teeth of the rotor is determined by the diameter of a base circle and the diameters of an externally rolling circle and an internally rolling circle which form the tooth profile by rolling on the base circle without slipping thereon. Further, since the tooth depth of the rotor is determined by the diameters of the externally rolling circle and the internally rolling circle, the discharge amount of the pump depends on the diameters of the base circle and the rolling circles. For this reason, the degree of flexibility in setting the tooth depth and the number of teeth is low, and it is difficult to meet the demand to increase the discharge amount of the pump.
In addition, in the internal gear pump, as the number of teeth increases, the number of discharge operations from a pump chamber (pumping chamber) performed during one rotation of the inner rotor increases. Hence, pulsation of discharge pressure decreases. However, when the number of teeth is increased while satisfying the discharge amount in the conventional internal gear pump, as described above, the rotor size increases. Therefore, the increase in number of teeth is restricted.
An object of the present invention is to increase the discharge amount of a pump and to suppress discharge pulsation by allowing flexibility in setting the tooth depth of a pump rotor that includes in combination an inner rotor and an outer rotor whose numbers of teeth are different by one.
In order to achieve the above object, in the present invention, an internal gear pump rotor including an inner rotor having n-number of teeth and an outer rotor having (n+1)-number of teeth in combination is configured as follows.
That is, formation circles B and C move in a manner such as to satisfy the following conditions, and at least one of an addendum curve and a dedendum curve of a tooth profile is formed by a locus curve drawn, during the movement, by one point j that coincides with a reference point J on a base circle A concentric with an inner rotor center OI and that is on the formation circles B and C.
—Moving Conditions of Formation Circles B and C—
While changing distances between the inner rotor center OI and centers pa of the formation circles by a distance R, the centers pa of the formation circles B and C move from moving start points Spa and Spb where the centers are positioned when the formation circles B and C are arranged so that the point j coincides with the reference point J on the base circle A, to moving end points Lpa and Lpb where the centers are positioned when the formation circles B and C are arranged so that the point j is positioned at an addendum top TT or a dedendum bottom TB. During this, the formation circles B and C rotate through an angle θ at a constant angular velocity in the same direction as moving directions of the circles.
As the formation circles B and C, two circles, that is, a circle whose center moves from the moving start point to the moving end point while keeping its diameter Bd or Cd fixed, and a circle whose center moves from the moving start point to the moving end point while decreasing its diameter Bd or Cd, are conceivable. An appropriate one of the formation circles can be selected in consideration of the required performance of the pump.
In the internal gear pump rotor, preferably, the centers pa of the formation circles move on curves ACI and AC2 where a change rate of the distances between the inner rotor center OI and the centers of formation circles is 0 at the moving end points Lpa and Lpb.
Preferably, the curves AC1 and AC2 are curves using a sine function. For example, the curves AC1 and AC2 are curves in which the displacement value ΔR of the distance from the inner rotor center OI satisfies the following expression:
ΔR=R×sin(π/2×m/ST)
where ST is the number of steps and m=0→ST.
Assuming that a straight line connecting the reference point J on the base circle A and the inner rotor center OI is designated as L1, an addendum top TT is set on a straight line L2 turned by an angle θT from the straight line L1, and a dedendum bottom TB is set on a straight line L3 turned by an angle θB from the straight line L1. Further the angle θT between the straight line L1 and the straight line L2 and the angle θB between the straight line L1 and the straight line L3 are set in consideration of, for example, the number of teeth and the ratio of setting areas of an addendum and a dedendum.
The moving start point Spa of the center of the addendum formation circle B and the moving start point Spb of the center of the dedendum formation circle C are on the straight line L1. Further, the moving end points Lpa and Lpb thereof are on the straight lines L2 and L3, respectively.
The present invention also provides an internal gear pump rotor including an inner rotor having the above-described tooth profile and the following outer rotor in combination.
A tooth profile of the outer rotor is determined by the following steps:
A center OI of the inner rotor makes one revolution on a circle S centered on the center of the outer rotor and having a diameter (2e+t).
During this, the inner rotor makes a 1/n rotation.
An envelope of a group of tooth profile curves formed by the revolution and rotation of the inner rotor is drawn.
The envelope thus determined serves as the tooth profile.
Here:
Here, the tip clearance is defined as follows:
First, the inner rotor is set in a state in which the inner rotor center is at the origin and an addendum top of the inner rotor is in a negative area on the Y-axis passing through the origin.
Next, the outer rotor is set in a state in which the center of the outer rotor is at one point on the Y-axis at a distance, which is equal to the amount of eccentricity e, from the origin and an addendum top of the outer rotor meets the addendum top of the inner rotor in the negative area on the Y-axis.
Then, from this state, the outer rotor center is moved on the Y-axis away from the inner rotor center until the tooth profile of the inner rotor and the tooth profile of the outer rotor come into contact with each other. At a measurement position of a tip clearance formed in this way, a clearance formed between the addendum top of the inner rotor on the Y-axis and the addendum top of the outer rotor on the Y-axis serves as the tip clearance t.
The present invention further provides an internal gear pump in which the above-described internal gear pump rotor of the present invention is stored in a rotor accommodating chamber provided in a pump housing.
When the addendum formation circle B and the dedendum formation circle C have diameters that change during movement, diameters Bdmax and Cdmax of the formation circles at the moving start points are set in consideration of the target tooth depth. Assuming that the change amounts of diameter of the formation circles between the moving start points and the moving end points are ΔBd and ΔCd, the addendum height and the dedendum depth for determining the tooth depth are given by the following expressions:
addendum height=R+(Bd/2)+{(Bd−ΔBd/2)}
dedendum depth=R+(Cd/2)+{(Cd−ΔCd/2)}
In these two expressions, R, Bd, ΔBd, Cd, and ΔCd are all numerical values that can be set arbitrarily. Adequate values of R, Bd, ΔBd, Cd, and ΔCd can be found, for example, by producing some tooth profile models in which these values are variously changed in consideration of the change rate of the moving distance R and selecting the best one from the models.
Appropriate diameters of the formation circles B and C at the moving end points Lpa and Lpb are more than or equal to 0.2 times the diameters at the moving start points Spa and Spb and less than or equal to the diameters at the moving start points Spa and Spb.
For example, a tooth profile using a cycloidal curve is drawn by a locus of one point on each of an internally rolling circle and an externally rolling circle with a fixed diameter that roll on a base circle having a fixed diameter. To establish the tooth profile, the internally rolling circle and the externally rolling circle each must move around the base circle when making the same number of rotations as the number of teeth. For this reason, the shape of the rotor is determined by the diameter of the base circle, the diameters of the rolling circles, and the number of teeth. Since the tooth depth is determined by the diameters of the rolling circles for themselves, there is no flexibility in changing the tooth depth. This also applies to a tooth profile formed using a trochoidal curve.
In contrast, in the internal gear pump rotor of the present inventor, in the tooth profile of at least one of the addendum and the dedendum of the inner rotor, the formation circle does not roll on the base circle having a fixed diameter. While the formation circle rotates through the angle θ at a constant angular velocity, it does not roll on the base circle.
In
In particular, the tooth depth can be freely increased by setting the radial moving distances R at zero or more. The increase in tooth depth increases the capacity of a pump chamber defined between the teeth of the inner rotor and the outer rotor, and thereby increases the discharge amount of the pump.
In the internal gear pump rotor of the present invention, since conditions, such as the diameters of the formation circles, the radial moving distances of the formation circles, and the change rate of the distances, can be freely set, the degree of flexibility in designing the tooth profile also increases.
In particular, when the tooth profiles of the addendum and the dedendum of the inner rotor are formed using the formation circles that move while changing their diameters, they can be changed by changing the change amounts of diameter from the moving start points to the moving end points of the formation circles. Hence, the degree of flexibility in designing the tooth profile increases further.
Details of the straight lines L1 to L3, the moving start point Spa and the moving end point Lpa of the center of the addendum formation circle B, the moving start point Spb and the moving end point Lpb of the center of the dedendum formation circle C, and the distances R0, R1, r0, and r1 will be given in the following description.
In the tooth profile formed using the tooth profile of a cycloidal curve, the tooth depth, which is the sum of diameters of the internally rolling circle and the externally rolling circle, is double the amount of eccentricity between the inner rotor and the outer rotor (hereinafter simply referred to as the amount of eccentricity). Further, as described above, to establish the tooth profile, the internally rolling circle and the externally rolling circle each must move around the base circle when making the same number of rotations as the number of teeth. Thus, if the diameter of the base circle and the amount of eccentricity are determined, the number of teeth is also determined. For this reason, there is no flexibility in designing the number of teeth when the rotor size is not changed. This also applies to a tooth profile formed using a trochoidal curve. In contrast, the pump rotor of the present invention has no concept of a base circle, and the number of teeth can be determined, regardless of the base circle and the amount of eccentricity. For this reason, there is flexibility in setting the number of teeth. Hence, it is possible to reduce discharge pulsation of the pump by increasing the number of teeth.
A pump rotor according to an embodiment of the present invention will be described below with reference to
A tooth profile of the inner rotor 2 is formed using a base circle A that is concentric with the inner rotor, and a formation circle B and/or a dedendum formation circle C having a point j that is provided on the circumference thereof and passes through a reference point J serving as an intersection of the base circle A and the Y-axis. As a concrete example of a tooth profile, a combination of addendums and dedendums formed according to the following conditions is conceivable. The base circle A is a circle having a radius extending from the inner rotor center to a boundary point between the addendum and the dedendum, and the point j starts to move from a position on the circle.
It is assumed, in
The center pa of the addendum formation circle B moves toward the straight line L2 through the angle θT from the moving start point Spa (this is a center position of the addendum formation circle B at a position where the point j coincides with the reference point J, and the moving start point Spa is on the straight line L1 in
During this, the center pa of the addendum formation circle B moves by a distance R in the radial direction of the base circle A.
While the center pa of the addendum formation circle B moves from the moving start point Spa to the moving end point Lpa, the addendum formation circle B rotates through an angle θ and the point j on the formation circle moves from the reference point J to the addendum top TT. As illustrated at
In this case, the rotating direction of the addendum formation circle B is the same as the moving direction of the angle θT. That is, when the rotating direction is right-handed, the moving direction of the addendum formation circle B is also right-handed.
By inverting the drawn tooth profile curve with respect to the straight line L2 (so as to be symmetrical with respect to the straight line L2), an addendum curve of the inner rotor is obtained.
A dedendum curve can be drawn similarly. A center pa of the dedendum formation circle C having a diameter Cd is moved from a moving start point Spb toward a moving end point Lpb through an angle θB while causing the dedendum formation circle C to rotate at a constant angular velocity in a direction opposite the rotating direction of the addendum formation circle B.
In this case, half of a tooth profile of the dedendum of the inner rotor is drawn by a locus formed when one point j on the circumference of the dedendum formation circle C moves from the reference point J to a dedendum bottom TB set on a straight line L3. Therefore, as illustrated at
In tooth profile formation by the above-described methods, the addendum formation circle B and the dedendum formation circle C move from the moving start points to the moving end points while keeping their diameters Bd and Cd constant, and half of the tooth profile of the addendum 2a of the inner rotor is drawn by the locus of the point j formed during movement. However, the tooth profile forming method is not limited to these methods. The object of the present invention is also achieved by a method in which the addendum formation circle B and the dedendum formation circle C move from the moving start points to the moving end points while changing their diameters, and halves of the tooth profiles of the addendum and dedendum of the inner rotor are drawn by the loci of the points j formed during movement.
It is assumed, in
The center pa of the addendum formation circle B moves toward the straight line L2 through the rotation angle θT from the moving start point Spa to the moving end point (this is on the straight line L2). In this case, the circumferential angular velocity of the center pa of the addendum formation circle B is fixed.
During this, the center pa of the addendum formation circle B moves by a distance R in the radial direction of the base circle A.
The addendum formation circle B rotates through the angle θ while decreasing its diameter during a period in which the center pa of the addendum formation circle B moves from the moving start point Spa to the moving end point Lpa. By displacement of the angle θ, the point j on the addendum formation circle B reaches the addendum top TT set on the straight line L2 (this is at a position where a preset addendum circle having a diameter DT intersects the straight line L2). Half of a tooth profile of an addendum 2a of the inner rotor is drawn by a locus formed when the point j moves during this. The diameter of the addendum formation circle B has changed to Bdmin at the addendum top TT. According to this method, the radius of curvature of the addendum can be made larger than in the tooth profile drawn using a formation circle having a fixed diameter. Further, it is possible to obtain a tooth profile in which the difference between the clearance near the tip clearance and the tip clearance is reduced.
Similarly to the case in which the tooth profile is formed using the formation circle having a fixed diameter, the rotating direction and the moving direction through the angle θT of the addendum formation circle B are made equal, and the tooth profile that is symmetric with respect to the straight line L2 is formed by inverting the half of the tooth profile, which is drawn by the above-described method, with respect to the straight line L2.
A dedendum curve can be drawn similarly. A dedendum formation circle C having a diameter Cd at a moving start point Spb is caused to rotate at a constant angular velocity in a direction opposite in the rotating direction of the addendum formation circle B, and is moved through an angle θB from the moving start point Spb toward a moving end point Lpb while decreasing its diameter. Half of a tooth profile of a dedendum of the inner rotor is drawn by a locus formed while one point j on the circumference of the dedendum formation circle C moves from the reference point J to a dedendum bottom TB set on the straight line L3 (this is at a position where a preset dedendum circle having a diameter DB intersects the straight line L3). By drawing the half tooth profile to be symmetrical with respect to the straight line L2, a dedendum shape for one tooth can be obtained.
The tooth profile can be formed by the above-described methods by presetting the number of teeth n, the diameter DT of the addendum circle, the diameter DB of the dedendum circle, the angle θT from the straight line L1 to the straight line L2 (∠SpaOITT), the angle θB from the straight line L1 to the straight line L3 (∠SpbOITB), the diameters Bdmax and Cdmax of the addendum formation circle B and the dedendum formation circle C at the moving start points, the diameters (Bdmin=Bd−ΔB) and (Cdmin=Cd−ΔCd) at the moving end points, and the curves on which the centers pa of the addendum formation circle B and the dedendum formation circle C move.
Preferably, the centers pa of the addendum formation circle B and the dedendum formation circle C move on curves AC1 and AC2 in which the change rate ΔR of the moving distance R is 0 at the moving end points Lpa and Lpb of the centers of the formation circles. In this case, the addendums do not become sharp, and the clearance near the tip clearance becomes stable. This achieves the effects of enhancing discharge performance (increasing the discharge amount), preventing noise during pump operation, and enhancing durability of the rotor.
Preferably, for example, the above-described curves AC1 and AC2 are curves using a sine function (the displacement value ΔR of the moving distance R is expressed by the following expression):
ΔR=R×sin(π/2×m/ST)
By doing this, the change rate is zero when m=ST, and a smooth curve can be drawn. In this case, a moving amount Δθ in the circumferential direction of the center pa of the formation circle is given as follows:
Δθ=θT/ST
Besides the sine curve that is preferable, a cosine curve, a higher curve, an arc, an elliptic curve, or a curve formed by a combination of these curves and a straight line having a fixed inclination can be used for the curves AC1 and AC2.
When the center of the addendum formation circle B moves from the moving start point Spa to the moving end point Lpa while the addendum formation circle B decreases its diameter, preferably, the change rate of the diameter of the addendum formation circle B is preferably zero at the moving end point Lpa and Lpb of the center of the formation circle. This can easily increase the radius curvature of the addendum. For example, the displacement value Δr satisfies the following expression using a sine function:
Δr=r×sin(π/2×m/ST)
where ST is the number of steps, and m=0→ST, r is the difference in radius of the formation circle between the moving end point and the moving start point.
The number of teeth of the outer rotor 3 (the number of teeth is seven in
Here:
In the inner rotor 2 having addendums to which the curve that characterizes the present invention and that has been described with reference to
The tooth profile using the tooth profile curve of the present invention and the cycloidal curve in combination allows smooth engage with the outer rotor that is characteristic of the cycloidal curve, and can increase the tooth depth. The demand to increase the discharge amount is thereby satisfied.
In the tooth profile to which the tooth profile curve of the present invention is applied, the addendum height and dedendum depth of the inner rotor are determined by the value of the radial moving distance R of the addendum formation circle B and the dedendum formation circle C. Since the value of the moving distance R can be freely set in the tooth profile to which the tooth profile curve of the present invention is applied, even when one of the addendum and the dedendum has a tooth profile defined by a trochoidal curve or a cycloidal curve, the degree of flexibility in setting the tooth depth is ensured.
The inner rotor 2 and the outer rotor 3 described above are eccentrically arranged in combination to form the internal gear pump rotor 1. As shown in
As described above, when the addendum of the tooth profile is formed, the center of the formation circle moves on the curve such that the distance from the inner rotor center to the center of the formation circle increases from the moving start end toward the moving terminal end. In contrast, when the dedendum of the tooth profile is formed, the center of the formation angle moves on the curve such that the distance decreases. During this, the formation circle rotates. Thus, the tooth profile of at least one of the addendum and the dedendum of the inner rotor 2 is formed by the locus of one point on the circumference of the formation circle. By doing this, the tooth depth of the inner rotor can be made larger than the tooth depth in the conventional internal gear pump that adopts a tooth profile of a trochoidal curve or a tooth profile of a cycloidal curve. For this reason, the capacity of the pump chamber 4 defined between the teeth of the inner rotor 2 and the outer rotor 3 becomes larger than in the conventional pump, and this increases the discharge amount of the pump.
Alternatively, by doing this, the number of teeth of the inner rotor can be made larger than the number of teeth of the conventional internal gear pump that adopts the tooth profile of a trochoidal curve or the tooth profile of a cycloidal curve. For this reason, the number of pump chambers 4 defined between the teeth of the inner rotor 2 and the outer rotor 3 becomes larger than in the conventional pump, and this increases the discharge amount of the pump.
Further, since the condition of tooth profile formation can be freely set, the degree of flexibility in designing the tooth profile increases. When an addendum curve or a dedendum curve of the inner rotor is formed using the addendum formation circle or the dedendum formation circle whose diameter decreases by a fixed amount per fixed rotation angle, the degree of flexibility in designing the tooth profile is particularly high because the clearance near the tip clearance can be adjusted by changing the shape of the addendum.
Here are results of a performance evaluation test conducted on the pump rotor of the present invention. An inner rotor having six teeth and an outer rotor having seven teeth, which were formed of an iron sintered alloy, were produced, and the rotors were combined into an internal gear oil pump rotor.
Combinations of addendum and dedendum curves of the inner rotor used in the test are follows:
First Comparative Example (see
First Invention (see
Second Invention (see
Third Invention (see
Fourth Invention (see
Common specifications are as follows:
outer diameter of outer rotor: 60 mm
inner diameter of inner rotor: 15 mm
rotor thickness: 15 mm
Tooth profiles were formed by the following methods. In this case, a tooth profile of any outer rotor was formed by an envelope of tooth profile curves found by the method shown in
In a first comparative example, a cycloidal curve of an addendum was formed by rolling an externally rolling circle having a diameter of 3.25 mm on a base circle having a diameter of 39 mm without slipping thereon. A cycloidal curve of a dedendum was formed by rolling an internally rolling circle having a diameter of 3.25 mm on the base circle having a diameter of 39 mm without slipping thereon.
Addendum diameters (diameters of addendum circles) and dedendum diameters (diameters of dedendum circles), and the amount of eccentricity e of the formed inner and outer rotors are as follows:
addendum diameter of inner rotor: 45.5 mm
dedendum diameter of inner rotor: 32.5 mm
addendum diameter of outer rotor: 39.1 mm
dedendum diameter of outer rotor: 52.1 mm
amount of eccentricity e: 3.25 mm
[First Invention]
A tooth profile curve of the present invention at a dedendum was formed by the method shown in
diameter Ad of base circle A: 41.0 mm
diameter Cd of formation circle C: 4.5 mm
radial moving amount R of formation circle C: 2.3 mm
displacement value ΔR of moving distance R: 2.3×sin(π/2×m/ST)
number of steps ST: 30
θB: 19.5°
Addendum diameters and dedendum diameters, and the amount of eccentricity e of the formed inner and outer rotors are as follows. These numerical values are also the same in the following second, third, and fourth inventions.
addendum diameter of inner rotor: 45.1 mm
dedendum diameter of inner rotor: 31.5 mm
addendum diameter of outer rotor: 38.3 mm
dedendum diameter of outer rotor: 51.9 mm
amount of eccentricity e: 3.4 mm
[Second Invention]
In a second invention, a tooth profile curve of the present invention at an addendum was formed by the method shown in
diameter Ad of base circle A: 40.0 mm
diameter Bd of formation circle B: 2.3 mm
radial moving amount R of formation circle B: 1.1 mm
displacement value ΔR of moving distance R: 1.1×(m/ST)
number of steps ST: 30
θB: 10.5°
A tooth profile curve of the present invention at a dedendum was formed by the method shown in
diameter Ad of base circle A: 40.0 mm
diameter Cd of formation circle C: 4.3 mm
radial moving amount R of formation circle C: 2.0 mm
displacement value ΔR of moving distance R: 2.0×sin(π/2×m/ST)
number of steps ST: 30
θT: 19.5°
[Third Invention]
diameter Ad of base circle A: 40.0 mm
diameter Bd of formation circle B: 2.3 mm
radial moving distance R of formation circle B: 1.1 mm
displacement value ΔR of moving distance R: 1.1×sin(π/2×m/ST)
number of steps ST: 30
θT: 10.5°
A tooth profile curve of the present invention at a dedendum was formed by the method shown in
diameter Ad of base circle A: 40.0 mm
diameter Cd of formation circle C: 4.3 mm
radial moving amount R of formation circle C: 2.0 mm
displacement value ΔR of moving distance R: 2.0×sin(π/2×m/ST)
number of steps ST: 30
θT: 19.5°
In a fourth invention, a tooth profile curve of the present invention at an addendum was formed by the method shown in
diameter Ad of base circle A: 41.4 mm
diameter Bdmax of addendum formation circle B at moving start point: 2.4 mm
diameter Bdmin at moving end point: 0.6 mm
displacement value of diameter of addendum formation circle: Δr=1.8×sin(π/2×m/ST)
radial moving distance R of center of addendum formation circle B: 0.7 mm
displacement value of moving distance R: ΔR=0.7×sin(π/2×m/ST)
number of steps ST: 30
θT: 10.5°
A tooth profile curve of the present invention at a dedendum of the fourth invention was formed by the method shown in
diameter of base circle A: 41.4 mm
diameter Cdmax of dedendum formation circle C at moving start point: 4.5 mm
diameter Cdmin at moving end point: 4.0 mm
displacement value of diameter of dedendum formation circle: Δr=0.5×sin(π/2×m/ST)
radial moving distance R of center of dedendum formation circle C: 2.9 mm
displacement value ΔR of moving distance R: 2.9×sin(π/2×m/ST) number of steps ST: 30
θB: 19.5°
Internal gear pumps were constructed by incorporating, into the pump housing, the internal gear pump rotors formed by combining the inner rotors and the outer rotors having the above-described specifications. Then, discharge amounts of the pumps provided under the following test conditions were compared. The result of comparison is shown in the following Table I.
Test Conditions
TABLE I
Test result
Discharge amount (L/min)
Comparative example
31.8
First invention
32.6
Second invention
32.7
Third invention
33.0
Fourth invention
33.5
As is seen from this test result, by changing the distance R, the tooth depth of the rotor and the discharge amount of the pump can be made larger than in the conventional pump in which the tooth profile of the inner rotor is formed by a trochoidal curve (see
In the fourth invention in which the diameter of the formation circle is gradually changed during movement, the discharge amount increases, compared with the comparative example. From this result, it is shown that the object of the present invention can be achieved even when the diameter of the formation circle changes during movement.
The pump rotor and the internal gear pump according to the present invention can be preferably used, for example, as oil pumps for lubrication of the car engine and for an automatic t transmission (AT).
Reference Numerals
1
pump rotor
2
inner rotor
2
addendum
2b
dedendum
2c
shaft hole
3
outer rotor
4
pump chamber
5
pump housing
6
rotor chamber
7
suction port
8
discharge port
9
internal gear pump
A
base circle
Ad
diameter of base circle A
B
addendum formation circle
Bd
diameter of addendum formation circle B
Spa
moving start point of addendum formation circle B
Lpa
moving end point of addendum formation circle B
Bdmax
diameter of addendum formation circle B at
moving start point
Bdmin
diameter of addendum formation circle B at
moving end point
ΔBd
change amount of diameter of addendum
formation circle B
C
dedendum formation circle
Cd
diameter of dedendum formation circle C
Spb
moving start point of dedendum formation circle C
Lpb
moving end point of dedendum formation circle C
Cdmax
diameter of dedendum formation circle C at
moving start point
Cdmin
diameter of dedendum formation circle C at
moving end point
ΔCd
change amount of diameter of dedendum
formation circle C
AC1
curve on which center of addendum formation
circle B moves
AC2
curve on which center of dedendum formation
circle C moves
J
reference point on base circle A
j
one point on formation circle
TT
addendum top of inner rotor
TB
dedendum bottom of inner rotor
L1
straight line connecting center OI of inner rotor and
reference point J
L2
straight line connecting center OI of inner rotor and
addendum top TT
L3
straight line connecting center OI of inner rotor and
dedendum bottom TB
θT
rotation angle from straight line L1 to straight line
L2 (∠SpaOITT)
θB
rotation angle from straight line L1 to straight line
L3 (∠SpbOITB)
R
radial moving distance of formation circle
ΔR
displacement value of distance R
pa
center of formation circle
R0, R1
distance from center OI of inner rotor to center of
addendum formation circle B
r0, r1
distance from center OI of inner rotor to center of
dedendum formation circle C
DT
diameter of addendum circle of inner rotor
DB
diameter of dedendum circle of inner rotor
e
amount of eccentricity between inner rotor
and outer rotor
t
tip clearance
n
number of teeth of inner rotor
OI
center of inner rotor
OO
center of outer rotor
S
circle having diameter of 2e + t
E
base circle
F
rolling circle
TC
trochoidal curve
G
locus circle
Yoshida, Kentaro, Uozumi, Masato, Sasaki, Harumitsu, Egami, Yuichirou
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| Aug 04 2009 | SUMITOMO ELECTRIC SINTERED ALLOY, LTD. | (assignment on the face of the patent) | / | |||
| Mar 10 2010 | UOZUMI, MASATO | SUMITOMO ELECTRIC SINTERED ALLOY, LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 024201 | /0333 | |
| Mar 11 2010 | SASAKI, HARUMITSU | SUMITOMO ELECTRIC SINTERED ALLOY, LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 024201 | /0333 | |
| Mar 11 2010 | YOSHIDA, KENTARO | SUMITOMO ELECTRIC SINTERED ALLOY, LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 024201 | /0333 | |
| Mar 18 2010 | EGAMI, YUICHIROU | SUMITOMO ELECTRIC SINTERED ALLOY, LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 024201 | /0333 |
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